[OPENNLP-1330] Parser top k parses doesn't show "top" (highest probability) parses.

• Type: Bug
• Status: Closed
• Priority: Minor
• Resolution: Fixed
• Affects Version/s: 1.9.3
• Fix Version/s: 1.9.4
• Component/s: Parser
• Labels: Parser
• Flags: Patch
• Assignee: Unassigned
• Reporter: Eric Ihli
• Created: 10/Jun/21 05:10
• Updated: 23/Jun/21 12:37
• Resolved: 23/Jun/21 12:36

Description

 The default "top n parses" of 1 shows the most likely parse; one with a log prob of -2.9.

Passing in anything greater than 1 returns the least probable parses.

➜ bin git:(master) echo "Eric is testing." | ./opennlp Parser -k 1 ~/src/prhyme/resources/models/en-parser-chunking.bin
Loading Parser model ... done (2.515s)
0 -2.913239374955309 (TOP (S (NP (NNP Eric)) (VP (VBZ is)) (. testing.)))

Average: 41.7 sent/s
Total: 1 sent
Runtime: 0.024s
Execution time: 2.585 seconds
➜ bin git:(master) echo "Eric is testing." | ./opennlp Parser -k 2 ~/src/prhyme/resources/models/en-parser-chunking.bin
Loading Parser model ... done (2.578s)
0 -14.968552218782305 (TOP (S (NP (NNP Eric)) (SBAR (S (ADVP (VBZ is)) (VBG testing.)))))
1 -13.957766393572408 (TOP (S (SBAR (S (NP (NNP Eric)) (ADVP (VBZ is)))) (VBG testing.)))

Average: 95.2 sent/s
Total: 2 sent
Runtime: 0.021s
Execution time: 2.640 seconds

 The fix is clear and simple. We should be taking from the first of the TreeSet rather than from the end.

 else if (numParses == 1) {
 return new Parse[] {completeParses.first()};
 }
 else {
 List<Parse> topParses = new ArrayList<>(numParses);
 while (!completeParses.isEmpty() && topParses.size() < numParses) {
 Parse tp = completeParses.last();      //// <--- Change to .first()
 completeParses.remove(tp);
 topParses.add(tp);
 //parses.remove(tp);
 }
 return topParses.toArray(new Parse[topParses.size()]);
 }

After patch, results are what I expect.

 

➜ bin git:(master) ✗ echo "Eric is testing." | ./opennlp Parser -k 1 ~/src/prhyme/resources/models/en-parser-chunking.bin
Loading Parser model ... done (2.517s)
0 -2.913239374955309 (TOP (S (NP (NNP Eric)) (VP (VBZ is)) (. testing.)))

Average: 45.5 sent/s
Total: 1 sent
Runtime: 0.022s
Execution time: 2.580 seconds
➜ bin git:(master) ✗ echo "Eric is testing." | ./opennlp Parser -k 2 ~/src/prhyme/resources/models/en-parser-chunking.bin
Loading Parser model ... done (2.530s)
0 -2.913239374955309 (TOP (S (NP (NNP Eric)) (VP (VBZ is)) (. testing.)))
1 -3.1132674983145825 (TOP (S (NP (NNP Eric)) (VP (VBZ is) (NP (NN testing.)))))

Average: 90.9 sent/s
Total: 2 sent
Runtime: 0.022s
Execution time: 2.596 seconds